Getter apparatus



Patented Aug. 26, 1947 2,426,247 GETTER APPARATUS Benjamin signor toFranklin Steiger,

United Electronics Company, Newark,

Maplewood, N. J as- N. J a corporation of New Jersey Application March24, 1943, Serial No. 480,283

This invention relates to apparatus for and the method of introducinggetter into vacuum tubes.

For many years it has been customary to introduce getter into highlyevacuated tubes such as those used for radio transmission and reception,for example, in order to improve the vacuum within such tubes. It hasbeen found, however, that in the case of high frequency and high voltagetubes employing a high vacuum that the introduction of getter, althoughdesirable, presented many difficulties so that it is now the practicenot to use any getter in such tubes. The difficulties which have beenencountered when a getter has been used in such tubes have beenprimarily that the getter would deposit on the electrodes or otherportions of the tube within the envelope with undesirable results. Forexample, if any of the getter were deposited on the electrodes withinthe tube, the electrodes would become primary emitters of electrons sothat the tube would either change its characteristics or cease tofunction. This is particularly true in case any getter becomes depositedon the inside of the plate. The plate begins to emit electrons and thetube either immediately or after an interval ceases to be' useful toperform its desired function. If any getter becomes deposited on thepress or stem of the tube or upon the envelope itself, a high voltagepuncture is likely to occur particularly in the stem, thus destroyingthe tube entirely.

I have discovered that a getter may be used in a high voltage, highvacuum tube such as a rectifier tube used in a radio transmitter, forexample, with apparatus according to my invention in which the getter isprevented from being deposited upon any of the electrodes of the tube orany portion of the tube itself. With my apparatus, I may confine thegetter deposit to the inside of a supplementary open ended tube withinthe evacuated envelope and thus secure the beneficial effects of using agetter without incurring any of the disadvantages which have heretoforeaccompanied such use in this type of tube.

In the drawings I have illustrated in Figure l a high vacuum, highvoltage rectifier for use in a radio transmitter which has been built inaccordance with my invention.

Figure 2 is an enlarged section along the lines 2-2 of Figure 1.

Figure 1 shows an envelope I having mounted therein an anode 2 whichsurrounds an elongated filamentary cathode maintined taut by the spring3. Rods 4 and 5 mounted in the press 2 Claims. (01. 206-0.4)

, cuit including the yoke 1 and rod I ll.

support the filament at its lower end. Secured to one or both of therods 4 and 5 in any suitable manner, as by a rod 6, is the getterstructure of myinvention. Secured to the rod 6 is a yoke I whichsupports a wire mesh 8 which in turn surrounds and supports an openended tube 9 which is illustrated as a glass tube, but may be of othermaterial, such as metal. Secured to the ends of the yoke 1 is a metalrod H! which has affixed to it a strip of getter material H. The getterstrip ll may be of any suitable materials, for example that soldcommercially under the trade name Kic Kemit, or it may be of any othersuitable material. One very good material to use as a getter, eitheralone or in combination with other materials, is barium, but barium is anotatable example of the type of getter which, if used in accordancewith usual practice in a high vacuum, high voltage tube, is subject tothe disadvantages mentioned above. The tube 9 surrounds the strip ofgetter H throughout the entire length of that strip. After the tube hasbeen thoroughly baked and evacuated in accordance with the usualpractice, the getter may be vaporized in any suitable manner, as forexample by applying a high frequency coil to the getter structure so asto induce current around the cir- This should be done in such a manneras to avoid flashing the getter, but instead to cause the getter toevaporate. This may be accomplished very simply by simply not applyingtoo strong a field for too long a time, that is, by avoiding too high adegree of heat. As the evaporation from any body occurs in straightlines perpendicular to its surface, the getter which is thus evaporatedpasses directly to the open ended tube 9 and is deposited thereon. Asthis tube is open at its ends and as the getter is evaporated graduallythere is no building up of pressure within the tube 9 such as wouldforce any of the evaporated getter material out of the ends of this tubeso that it is all deposited upon the inner surface of tube 9. Again, asthe tube 9 is open at its ends it is, of course, in communication with,indeed a part of, the evacuated space within the bulb and the getter is,therefore, just as effective in cleaning up any residual gas remainingwithin the tube as it would be if used in accordance with priorpractice.

In addition to the other advantages of my new apparatus and methodmentioned above, the introduction of getter in this manner prevents anydiscoloration whatever of the envelope of the bulb so that it remainsperfectly clear and transparent for easy viewing of the interior of thetube both in inspection at the time of manufacture and in use.

I have produced tubes in accordance with the method disclosed herein,and having the structure disclosed, and have found such tubes to haveall of the advantages Which would be expected from the additionaevacuation effect provided by the getter material, but Without any ofthe disadvantages that have heretofore inevitably accompanied previousattempts to use a getter in high vacuum, high voltage rectifier What isclaimed is:

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,712,370 White May 7, 19291,966,226 Sutherlin July 10, 1934 2,043,724 Anderson June 9, 19362,154,131 Lederer Apr, 11, 1939 2,183,841 King Dec. 19, 1939 2,093,273Haslauer Sept. 14, 1937 1,895,867 Sinden s Jan 31, 1933 1,917,044Loewe 1. 1. July 4, 1933

